This invention relates to data-entry keyboards, for example, keyboards of the type typically used with computers.
In membrane-type keyboards, electrical switches or sensors, one for each key of the keyboard, are arranged on a membrane. The membrane is typically a thin sheet of plastic. The membrane lies flat on a keyboard frame or base plate. As a key is depressed or released, the corresponding switch or sensor controls an electrical signal on one or more wires that are disposed on the membrane. These wires extend from the site of each switch or sensor to an electrical interconnect region of the membrane, where electrical connections are made between the wires on the membrane and the rest of the keyboard, typically at a rigid contact mounting. This contact mounting is typically a printed circuit board (PCB). Typically, this PCB is located in the upper-right corner of the keyboard, above the numeric keypad at the right of the keyboard and to the right of the row of “PF” keys, or toward the bottom of the keyboard. Typically, this PCB mounts electronics for decoding the signals on the wires to determine which key was pressed or released, and for generating signals that convey this key information to a computer. This PCB may also include LED's or other display elements to show “caps lock” or other status information. These functions may be divided between two or more PCB's located at several places throughout the keyboard.